Fire-spitting pulsejet engine delivers bulk thrust at low cost

Fire-spitting pulsejet engine delivers bulk thrust at low cost
Wave's J-1 engine gets flight testing atop its Scitor demonstrator UAV
Wave's J-1 engine gets flight testing atop its Scitor demonstrator UAV
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Wave's J-1 engine gets flight testing atop its Scitor demonstrator UAV
Wave's J-1 engine gets flight testing atop its Scitor demonstrator UAV
Graphic showing the Wave Engine's repeating cycle
Graphic showing the Wave Engine's repeating cycle

In an effort to create a simpler, more affordable form of jet propulsion, University of Maryland spinoff Wave Engine Corporation has developed a digitally controlled modern-day pulsejet engine for unmanned aerial vehicles (UAVs), a design that uses no moving parts. After officially launching its first engine back in March, the company announced this week that it's delivered the first customer engines. This loud, pulse-combustion fire-breather is officially on its way to more air-bound vessels.

To get more specific (but not much), Wave announced on Tuesday the delivery of the first J-1 engines to an "aerospace prime contractor on contract with the US government" – Bond-style hush-hush stuff. The company also says it has other customers working to integrate the J-1s into their UAV designs.

The J-1, a trombone-looking contraption that seems to be most at home atop the aircraft fuselage, is designed for high-speed UAVs with up to 200-lb (90-kg) gross vehicle weights. It weighs 18 lb (8.2 kg) and measures 5.5 x 12.5 x 64 inches (14 x 32 x 163 cm). It can run on a number of fuels, including gasoline, E85 bioethanol or kerosene-based jet fuel, putting out up to 55 lbf (245 N) of thrust.

In contrast to the rotational components used in other jet engines, Wave's pulsejet eliminates the need for moving parts. Instead, it relies exclusively on combustion-driven pressure waves to push out hot gases and create thrust.

The combustion takes place intermittently when fuel and air ignite in the chamber, increasing temperature and pressure to push hot gasses out of both ends of the tube and create thrust. The process results in a partial vacuum that causes the tube to suck fresh air in, starting the process over again for the next round of combustion and thrust.

Graphic showing the Wave Engine's repeating cycle
Graphic showing the Wave Engine's repeating cycle

Pulsejet engine technology has existed since the beginning of the 20th century, but Wave has updated it with modern technologies like electronic control and believes it ripe for the growing UAV industry. It declares it capable of high-speed propulsion at a lower cost and more rapid scalability than traditional jets.

Beyond the J-1, Wave is working on a larger K-1 engine that promises up to 220 lbf (979 N) of thrust for powering aircraft weighing up to 1,000 lb (454 kg). It also believes its technology has potential for larger commercial applications and a new class of high-speed VTOL. The engine family has been tested at air speeds of 200 mph (322 km/h).

"We are looking forward to working with our customers to increase production and bring an unmatched combination of cost, simplicity and flight performance to market," said Wave CEO Daanish Maqbool, looking ahead.

In the video below, you can watch the latest J-1-powered flight using Wave's Scitor-D UAV. This footage includes a sweet fireball-spewing start that we didn't see in the last video.

J-1 Wave Engine Complete Flight Footage

Source: Wave Engine Corporation

Is that a J1 or a V1?
Uncle Anonymous
I'm not sure how far they will get with this technology, but good luck to them.
So . . . not throttleable?
Pulse-jet engines are generally really loud (because of the rapidly repeating detonations). Unless they can make these things quieter than conventional jet/prop propulsion, I see a sad future for folks on the ground. (Also, not a good future for these things in weapons systems, since detection is pretty straightforward.)
Interesting that it can still suck in the air at 200mph. I'm surprised the nozzle doesn't create a vacuum behind it.
not that new, ever heard of the V-1?
Looks a lot like the old pop pop boat.
Imagino que possam ser usados vários tubos J em uma mesma aeronave e que a regulagem das explosões possam ocorrer via obturadores de ar e de combustível. A proporção entre comprimentos das extremidades dos tubos também podem mudar a frequência das explosões. O óxido nitroso pode implementar essa combustão.
Josef Faber
as mentioned by others, nothing new. this is old technology.
engine of this type were used in WWII by Germany.
it would be a slow moving target for today's weapons system.
the noise level alone preclude it's use.

The Lockwood-Hiller Design Valveless Pulse Jet
is a design very similar to the device in this article,
received U.S.Patent 3462955 26AUG1969
Yeah, that's what I was thinking: frigging buzzbombs.
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